Backport PR yt-project#3496: BUG: fix two bugs in yt.visualization.ep…

…s_writer

nose_unit.cfg

@@ -6,5 +6,5 @@ nologcapture=1
 verbosity=2
 where=yt
 with-timer=1
-ignore-files=(test_load_errors.py|test_load_sample.py|test_commons.py|test_ambiguous_fields.py|test_field_access_pytest.py|test_save.py|test_line_annotation_unit.py)
+ignore-files=(test_load_errors.py|test_load_sample.py|test_commons.py|test_ambiguous_fields.py|test_field_access_pytest.py|test_save.py|test_line_annotation_unit.py|test_eps_writer.py)
 exclude-test=yt.frontends.gdf.tests.test_outputs.TestGDF

tests/tests.yaml

@@ -189,6 +189,7 @@ other_tests:
      - '--ignore-files=test_load_sample.py'
      - '--ignore-files=test_field_access_pytest.py'
      - '--ignore-files=test_ambiguous_fields.py'
+     - '--ignore-files=test_eps_writer.py'
      - "--ignore-files=test_save.py"
      - '--exclude-test=yt.frontends.gdf.tests.test_outputs.TestGDF'
   cookbook:

yt/testing.py

@@ -7,6 +7,7 @@
 import shutil
 import tempfile
 import unittest
+from shutil import which
 
 import matplotlib
 import numpy as np
@@ -1364,6 +1365,29 @@ def ftrue(func):
     return ffalse
 
 
+def requires_external_executable(*names):
+    import pytest
+
+    def deco(func):
+        missing = []
+        for name in names:
+            if which(name) is None:
+                missing.append(name)
+
+        # note that order between these two decorators matters
+        @pytest.mark.skipif(
+            missing,
+            reason=f"missing external executable(s): {', '.join(missing)}",
+        )
+        @functools.wraps(func)
+        def inner_func(*args, **kwargs):
+            return func(*args, **kwargs)
+
+        return inner_func
+
+    return deco
+
+
 class TempDirTest(unittest.TestCase):
     """
     A test class that runs in a temporary directory and

yt/visualization/eps_writer.py

@@ -1,3 +1,5 @@
+import os
+
 import numpy as np
 import pyx
 from matplotlib import cm, pyplot as plt
@@ -743,7 +745,7 @@ def colorbar(
 
         # Convert the colormap into a string
         x = np.linspace(1, 0, 256)
-        cm_string = cm.get_cmap[name](x, bytes=True)[:, 0:3].tobytes()
+        cm_string = cm.get_cmap(name)(x, bytes=True)[:, 0:3].tobytes()
 
         cmap_im = pyx.bitmap.image(imsize[0], imsize[1], "RGB", cm_string)
         if orientation == "top" or orientation == "bottom":
@@ -1143,6 +1145,7 @@ def save_fig(self, filename="test", format="eps", resolution=250):
         >>> d = DualEPS()
         >>> d.axis_box(xrange=(0, 100), yrange=(1e-3, 1), ylog=True)
         """
+        filename = os.path.expanduser(filename)
         if format == "eps":
             self.canvas.writeEPSfile(filename)
         elif format == "pdf":

yt/visualization/tests/test_eps_writer.py

@@ -0,0 +1,28 @@
+import yt
+from yt.testing import fake_amr_ds, requires_external_executable, requires_module
+
+
+@requires_external_executable("tex")
+@requires_module("pyx")
+def test_eps_writer(tmp_path):
+    import yt.visualization.eps_writer as eps
+
+    fields = [
+        ("gas", "density"),
+        ("gas", "temperature"),
+    ]
+    units = [
+        "g/cm**3",
+        "K",
+    ]
+    ds = fake_amr_ds(fields=fields, units=units)
+    slc = yt.SlicePlot(
+        ds,
+        "z",
+        fields=fields,
+    )
+    eps_fig = eps.multiplot_yt(2, 1, slc, bare_axes=True)
+    eps_fig.scale_line(0.2, "5 cm")
+    savefile = tmp_path / "multi"
+    eps_fig.save_fig(savefile, format="eps")
+    assert savefile.with_suffix(".eps").exists()